The relative time clock is a mechanism designed for applications where the relative time between two or more events is important. It is especially useful in medical applications, where the age of datum is often more useful than the actual time that its capture took place. For instance, a doctor may wish to monitor the preterm uterine activity of a patient on a daily or twice daily basis for a period of a week. It would be inconvenient for a patient to make two daily trips to the doctor's office. Also the doctor may wish to have readings taken at times when the doctor's office is not normally open. It would be more efficient as well as convenient for the patient to make daily recordings at home, at various times, and then transmit that data at a later time over the phone lines to the doctor's office. In such an instance the doctor may want to know how long ago the various sets of data were recorded. By monitoring the relative time between the occurrence of various events the doctor will be able to determine age of the datum he is analyzing. The abovementioned events are detected by means of a pressure transducer such as the one disclosed in the patent application for a Pressure Transducer filed in the name of Charles S. Mitchell and filed with the U.S. Patent and Trademarks Office on Feb. 15, 1985, the disclosure of which is incorporated herein by reference.